The recent proliferation of rechargeable electronic devices, such as mobile telephones, PDA's and notebook computers has dramatically increased. Even when turned “off,” many of these devices continue to use power, referred to as “standby power” or “no-load power,” to operate features such as clocks, timers, touch pads, or to receive signals (e.g., from remote controls). Battery chargers, such as mobile phone chargers, and external power supplies (e.g., notebook computer power supplies) draw power when they are plugged in to an outlet, even if the associated device is fully charged or even disconnected.
Although the standby power consumption of most of these devices is relatively small, the number of devices drawing standby power is very large and is growing rapidly. For example, currently standby power may account for over 10 percent of all electric power used in a typical home. Environmental and economic considerations therefore make it desirable to significantly reduce the standby power of electronic equipment and chargers.
It is against this background that the techniques for reducing no-load (or standby) power in electronic devices described herein have been developed.